Transmission Over Temperature
The transmission temperature has exceeded normal range.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The transmission fluid is getting too hot, which can cause damage to the transmission components if not addressed.
What the computer is actually seeing
The ECU measures transmission fluid temperature and triggers this code if the temperature exceeds a pre-set threshold, often over 220°F (104°C).
What a healthy reading looks like
Normal transmission fluid temperature should be between 180°F (82°C) - 220°F (104°C).
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check transmission fluid level. Add fluid if low, then retest.
- 22. Inspect the wiring and connector for the transmission fluid temperature sensor for damage or corrosion.
- 33. Connect a scan tool to check actual transmission fluid temperature against the sensor reading.
- 44. If readings are inconsistent, replace the transmission fluid temperature sensor and retest.
- 55. If transmission fluid is excessively dirty or burnt, flush and replace the fluid, then retest.
- 66. Check for any external blockages in the transmission cooler; ensure it is functioning properly.
Common causes
- Low transmission fluid level
- Faulty transmission fluid temperature sensor
- Blocked transmission cooler
- High load conditions or towing
- Worn or damaged transmission components
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, driving with an overheating transmission can cause severe damage and should be addressed immediately.
Will this problem come back after repair?
If the root cause is correctly identified and fixed, it shouldn't return; however, monitor the transmission fluid temperature.
Why does this code sometimes pair with SPN 1502?
SPN 1502 indicates the transmission fluid temperature sensor circuit is faulty, which can lead to incorrect readings and trigger SPN 1503.
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